From a mercury(ii) bis(yldiide) complex to actinide yldiides

Abstract

The bis(yldiide) mercury complex, (L-Hg-L), [L = C(PPh3)P(S)Ph2] is prepared from the corresponding potassium yldiide and used to access the first substituted yldiide actinide complexes [(C5Me5)2An(L)(Cl)] (An = U, Th)...

A Metallocene Bis(phosphoranocarbene) of Uranium and a Probe of Its Reactivity with Alcohols

“…The reason for this sizable shift is unknown, but it may show a high sensitivity of the phosphorus chemical shift to the U−C−P bond angle upon transitioning from nearly linear in 1 to notably bent in 2. This sensitivity mirrors findings in previous studies documenting substantial upfield chemical shifts in the 29 Si NMR spectra of silicon nuclei within cyclometalated rings of uranium compounds. 39 Furthermore, the elimination of H 2 C�PPh 3 in the formation of 2 (Scheme 2) suggests that the reaction may proceed through an intramolecular σ-bond metathesis pathway, where one carbene ligand deprotonates a pendant aryl C−H bond.…”

“…More acute bond angles suggest greater crowding, pushing the Cp* ligands closer to each other. In the case of 1 , its C cent –U–C cent = 129.7(1)° bond angle is slightly more obtuse than for yldiide complex Cp* 2 UCl­[C­(PPh 3 )­P­(S)­Ph 2 ] (C cent –U–C cent = 124.96(3)°) but more acute than that found for amidinate acetate complex Cp* 2 U­[( i PrN) 2 C­(Me) ′ ]­(κ 1 -O 2 CMe) (C cent –U–C cent = 135.4°) (Table ). …”

“…On the other hand, the U–C carbene bond distance in 1 is equivalent to that reported for the mono(methandiide) complex [C(PPh 2 NSiMe 3 ) 2 ]­U(Cl)(μ-Cl) 2 ­Li(THF) 2 (U1–C1 = 2.310(4) Å) . Furthermore, the U–C carbene bonds in 1 are significantly shorter than the U–C yldiide = 2.555(3) Å found in yldiide compound Cp* 2 UCl[C(PPh 3 )P(S)Ph 2 ] …”

“…More acute bond angles suggest greater crowding, pushing the Cp* ligands closer to each other. In the case of 1, its C cent −U−C cent = 129.7(1)°bond angle is slightly more obtuse than for yldiide complex Cp* 2 UCl[C(PPh 3 )P(S)Ph 2 ] (C cent −U−C cent = 124.96(3)°) 29 but more acute than that found for amidinate acetate complex Cp* 2 U[ The most striking characteristic of 1 is the presence of the two short uranium−carbene bonds of U1−C1 = 2.322(5) Å and U1−C2 = 2.301(5) Å. The slight variation in the U− C carbene bond lengths may be a consequence of steric congestion or clashing between the proximal −PPh 3 groups.…”

“…36 Furthermore, the U−C carbene bonds in 1 are significantly shorter than the U−C yldiide = 2.555(3) Å found in yldiide compound Cp* 2 UCl[C(PPh 3 )P(S)Ph 2 ]. 29 With respect to other bond metrics, the ranges in the U1− C1−P1 and U1−C2−P2 bond angles in 1 are within the ranges seen in [(Me 3 Si) 2 N] 3 U�C(H)PPh 3 (U1−C1−P1 = 151.7(4)°) 22 and (Tren TIPS )U�C(H)PPh 3 (U1−C1−P1 = 162.1(2)°). 24 Finally, the C1−P1 = 1.680(5) and C2−P2 = 1.687(5) Å bond lengths are unexceptional and similar to those found for [(Me 3 Si) 2 N] 3 U�C(H)PPh 3 (C1−P1 = 1.679(8) Å) and free H 2 C�PPh 3 (C−P = 1.661(8) Å).…”